RESUMO
This study aimed to evaluate the clinical significance of diffusion tensor imaging (DTI) in the early diagnosis of pyramidal tract Wallerian degeneration (WD) and assessment of neurological recovery following cerebral infarction. This study included 23 patients with acute cerebral infarction and 10 healthy adult controls. All participants underwent both magnetic resonance imaging (MRI) and DTI scans. DTI images were analyzed using the Functional MRI of the Brain Software Library to determine the regions of interest (ROI) and obtain the mean diffusivity (MD) and fractional anisotropy (FA) value for each ROI. The correlation between FA or MD and postinfarction functional recovery of the nervous system was further analyzed to assess the feasibility of using a DTI scan in the evaluation of functional recovery of the nervous system in patients with cerebral infarction. DTI may be useful in detecting signals of early postinfarction pyramidal tract WD and is useful for the evaluation of postinfarction neurological recovery. Cerebral lesions were detected using MRI in all patients. It was found that in some patients, the FA value of the ipsilateral pyramidal tract on DTI was decreased as early as day 3 after the onset of infarction and in all patients by day 7. Subsequent correlation studies showed that the FA value of the ipsilateral pyramidal tract on day 13 was negatively correlated with the National Institutes of Health Stroke Scale score, but positively correlated with the Barthel Index, motricity index, and modified Rankin Scale scores.
Assuntos
Infarto Cerebral/complicações , Imagem de Tensor de Difusão , Degeneração Walleriana/diagnóstico , Degeneração Walleriana/etiologia , Degeneração Walleriana/reabilitação , Estudos de Casos e Controles , HumanosRESUMO
Friedreich's ataxia (FA) is the most frequent autosomal recessive ataxia and essentially considered a disease of the dorsal root ganglia and spinal cord. It is caused by homozygous GAA expansions in the Frataxin gene in most cases. Although only a few studies have addressed cerebral involvement in FA, cognitive symptoms have lately been emphasized. To evaluate brain damage in vivo, we employed whole-brain VBM and analysis of pre-defined regions of interest (ROIs) over the cerebellum to compare 24 patients with 24 age-and-sex-matched normal controls. (1)H-MRS of deep cerebral white matter (WM) was subsequently performed. Mean age of patients was 28 years (range 14-45), mean duration of disease was 14 years (range 5-28) and 11 were men. Mean length of shorter (GAA1) and longer (GAA2) alleles were 735 and 863, respectively. VBM analysis identified WM atrophy in the posterior cyngulate gyrus, paracentral lobule and middle frontal gyrus. ROIs over the infero-medial cerebellar hemispheres and dorsal brainstem presented gray matter atrophy, which correlated with duration of disease (r = -0.4). NAA/Cr ratios were smaller among patients (P = 0.006), but not Cho/Cr (P = 0.08). Our results provide evidence of axonal damage in the cerebellum, brainstem and subcortical WM in FA. This suggests that neuronal dysfunction is more widespread than previously thought in FA.
Assuntos
Encéfalo/patologia , Ataxia de Friedreich/diagnóstico , Imageamento por Ressonância Magnética/métodos , Espectroscopia de Ressonância Magnética/métodos , Sistema Nervoso/patologia , Adolescente , Adulto , Atrofia/etiologia , Atrofia/patologia , Atrofia/fisiopatologia , Encéfalo/fisiopatologia , Tronco Encefálico/patologia , Tronco Encefálico/fisiopatologia , Córtex Cerebelar/patologia , Córtex Cerebelar/fisiopatologia , Progressão da Doença , Feminino , Ataxia de Friedreich/fisiopatologia , Giro do Cíngulo/patologia , Giro do Cíngulo/fisiopatologia , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Córtex Motor/patologia , Córtex Motor/fisiopatologia , Sistema Nervoso/fisiopatologia , Valor Preditivo dos Testes , Prognóstico , Estudos Prospectivos , Sensibilidade e Especificidade , Degeneração Walleriana/etiologia , Degeneração Walleriana/patologia , Degeneração Walleriana/fisiopatologia , Adulto JovemRESUMO
In order to qualify and quantify nerve fiber lesion following an acute crush injury, a morphologic and morphometric study was carried out in 25 Wistar rats divided into five groups of five animals each according to the crushing load applied, i.e., 500, 1,000, 5,000, 10,000, and 15,000 g. The injury was produced under general anesthesia on a 5mm-long intermediate segment of the right sciatic nerve for 10 min using a dead-weight machine. The animals were killed with an excessive dose of anesthetics 72 h later and submitted to perfusion with a fixing solution through the abdominal aorta immediately after death. Both the right and left sciatic nerves were removed and prepared for histologic and morphometric examinations; 5 microm-thick sections stained with 1% Toluidine blue were examined under a light microscope equipped with a video camera linked to a computer loaded with a graphic program (KS 400). The morphometric studies included measuring total number of fibers, fiber density, fiber diameter, myelin fiber area, axon diameter, axon area and G ratio. The results showed that damage to the nerve fibers began to appear as early as with the 500 g load and was similar in all groups despite the load applied, increasing with the 10,000 and 15,000 g loads, although the external supporting tissues and small diameter fibers were preserved. The predominant type of lesion produced was axonotmesis.